Vectors Of Infectious Diseases Research Articles

Development of a novel adenovirus serotype 35 vector vaccine possessing an RGD peptide in the fiber knob and the E4 orf 4, 6, and 6/7 regions of adenovirus serotype 5

Adenovirus (Ad) vectors based on human adenovirus serotype 5 (Ad5) have attracted significant attention as vaccine vectors for infectious diseases. However, the effectiveness of Ad5 vectors as vaccines is often inhibited by the anti-Ad5 neutralizing antibodies retained by many adults. To overcome this drawback, we focused on human adenovirus serotype 35 (Ad35) vectors with low seroprevalence in adults. Although Ad35 vectors can circumvent anti-Ad5 neutralizing antibodies, vector yields of Ad35 vectors are often inferior to those of Ad5 vectors. In this study, we developed novel Ad35 vectors containing the Ad5 E4 orf 4, 6, and 6/7 or the Ad5 E4 orf 6 and 6/7 for efficient vector production, and compared their properties. These E4-modified Ad35 vectors efficiently propagated to a similar extent at virus titers comparable to those of Ad5 vectors. An Ad35 vector containing the Ad5 E4 orf 4, 6, and 6/7 mediated more efficient transduction than that containing the Ad5 E4 orf 6 and 6/7 in human cultured cells. Furthermore, insertion of an arginine-glycine-aspartate (RGD) peptide in the fiber region of an Ad35 vector containing the Ad5 E4 orf 4, 6, and 6/7 significantly improved the transgene product-specific antibody production following intramuscular administration in mice. The Ad35 vector containing the RGD peptide mediated efficient vaccine effects even in the mice pre-immunized with an Ad5.

Circadian regulation of locomotion, respiration, and arousability in adult blacklegged ticks (Ixodes scapularis)

The blacklegged tick, Ixodes scapularis, is an ectoparasitic arachnid and vector for infectious diseases, including Lyme borreliosis. Here, we investigate the diurnal activity and respiration of wild-caught and lab-reared adult ticks with long-term video recording, multi-animal tracking and high-resolution respirometry. We find male and female ticks are in a more active, more arousable state during circadian night. We find respiration is augmented by light, with dark onset triggering more frequent bouts of discontinuous gas exchange and a higher overall volume of CO2 respired. Observed inactivity during the day meets the criteria of sleep: homeostatic in nature, rapidly reversible, a characteristic pose, and reduced arousal threshold. Our findings indicate that blacklegged ticks are in a distinct, heightened state of activity and arousability during night and in dark, suggesting this period may carry higher risk for tick bites and subsequent contraction of tick-borne diseases.

The Mosquito Fauna of Arizona: Species Composition and Public Health Implications.

Arizona is home to many mosquito species, some of which are known vectors of infectious diseases that harm both humans and animals. Here, we provide an overview of the 56 mosquito species that have been identified in the State to date, but also discuss their known feeding preference and the diseases they can (potentially) transmit to humans and animals. This list is unlikely to be complete for several reasons: (i) Arizona's mosquitoes are not systematically surveyed in many areas, (ii) surveillance efforts often target specific species of interest, and (iii) doubts have been raised by one or more scientists about the accuracy of some collection records, which has been noted in this article. There needs to be an integrated and multifaceted surveillance approach that involves entomologists and epidemiologists, but also social scientists, wildlife ecologists, ornithologists, representatives from the agricultural department, and irrigation and drainage districts. This will allow public health officials to (i) monitor changes in current mosquito species diversity and abundance, (ii) monitor the introduction of new or invasive species, (iii) identify locations or specific populations that are more at risk for mosquito-borne diseases, and (iv) effectively guide vector control.

Wolbachia endosymbionts in Drosophila regulate the resistance to Zika virus infection in a sex dependent manner.

Drosophila melanogaster has been used extensively for dissecting the genetic and functional bases of host innate antiviral immunity and virus-induced pathology. Previous studies have shown that the presence of Wolbachia endosymbionts in D. melanogaster confers resistance to infection by certain viral pathogens. Zika virus is an important vector-borne pathogen that has recently expanded its range due to the wide geographical distribution of the mosquito vector. Here, we describe the effect of Wolbachia on the immune response of D. melanogaster adult flies following Zika virus infection. First, we show that the presence of Wolbachia endosymbionts promotes the longevity of uninfected D. melanogaster wild type adults and increases the survival response of flies following Zika virus injection. We find that the latter effect is more pronounced in females rather than in males. Then, we show that the presence of Wolbachia regulates Zika virus replication during Zika virus infection of female flies. In addition, we demonstrate that the antimicrobial peptide-encoding gene Drosocin and the sole Jun N-terminal kinase-specific MAPK phosphatase Puckered are upregulated in female adult flies, whereas the immune and stress response gene TotM is upregulated in male individuals. Finally, we find that the activity of RNA interference and Toll signaling remain unaffected in Zika virus-infected female and male adults containing Wolbachia compared to flies lacking the endosymbionts. Our results reveal that Wolbachia endosymbionts in D. melanogaster affect innate immune signaling activity in a sex-specific manner, which in turn influences host resistance to Zika virus infection. This information contributes to a better understanding of the complex interrelationship between insects, their endosymbiotic bacteria, and viral infection. Interpreting these processes will help us design more effective approaches for controlling insect vectors of infectious disease.

Visual attention is not attuned to non-human animal targets’ pathogenicity: an evolutionary mismatch perspective

A considerable amount of research has revealed that there exists an evolutionary mismatch between ancestral environments and conditions following the rise of agriculture regarding the contact between humans and animal reservoirs of infectious diseases. Based on this evolutionary mismatch framework, we examined whether visual attention exhibits adaptive attunement toward animal targets’ pathogenicity. Consistent with our predictions, faces bearing heuristic infection cues held attention to a greater extent than did animal vectors of zoonotic infectious diseases. Moreover, the results indicated that attention showed a specialized vigilance toward processing facial cues connoting the presence of infectious diseases, whereas it was allocated comparably between animal disease vectors and disease-irrelevant animals. On the other hand, the pathogen salience manipulation employed to amplify the participants’ contextual-level anti-pathogen motives did not moderate the selective allocation of attentional resources. The fact that visual attention seems poorly equipped to detect and encode animals’ zoonotic transmission risk supports the idea that our evolved disease avoidance mechanisms might have limited effectiveness in combating global outbreaks originating from zoonotic emerging infectious diseases.

Winged Threat on the Offensive: A Literature Review Due to the First Identification of Aedes japonicus in Poland.

Genetic studies preceded by the observation of an unknown mosquito species in Mikołów (Poland) confirmed that it belongs to a new invasive species in Polish fauna, Aedes japonicus (Theobald, 1901), a known vector for numerous infectious diseases. Ae. japonicus is expanding its geographical presence, raising concerns about potential disease transmission given its vector competence for chikungunya virus, dengue virus, West Nile virus, and Zika virus. This first genetically confirmed identification of Ae. japonicus in Poland initiates a comprehensive review of the literature on Ae. japonicus, its biology and ecology, and the viral infections transmitted by this species. This paper also presents the circumstances of the observation of Ae. japonicus in Poland and a methodology for identifying this species.

SPECIES DIVERSITY AND PREVALENCE OF ZOOPHILIC FLIES IN KOSTANAY REGION (NORTHERN KAZAKHSTAN)

This study delves into the understudied realm of zoophilic flies in the climatically distinct Kostanay region of Northern Kazakhstan. Amidst the region's diverse dipteran fauna, these parasitic flies pose a significant threat to both livestock and human health, acting as vectors for numerous infectious and invasive diseases. This study aimed to elucidate the spatiotemporal dynamics of zoophilic Diptera in the Kostanay region during the summer of 2023. As a result of the research, it was found that zoophilic flies of 8 families - representatives of 16 species - are registered on feedlots and pastures of farm animals of the Kostanay region of Northern Kazakhstan. Of these, the main species of flies (Musca domestica, M. stabulans, Calliphora unralensis, C. vicina and Wohlfartia magnifica) caused the greatest concern to animals. The total summer duration of zoophilic flies per season is 104-162 days or 3.5 - 5.5 months. Of the farm animals examined, cattle were the most intensively attacked.

A perspective on the impacts of microplastics on mosquito biology and their vectorial capacity.

Microplastics (plastic particles <5 mm) permeate aquatic and terrestrial ecosystems and constitute a hazard to animal life. Although much research has been conducted on the effects of microplastics on marine and benthic organisms, less consideration has been given to insects, especially those adapted to urban environments. Here, we provide a perspective on the potential consequences of exposure to microplastics within typical larval habitat on mosquito biology. Mosquitoes represent an ideal organism in which to explore the biological effects of microplastics on terrestrial insects, not least because of their importance as an infectious disease vector. Drawing on evidence from other organisms and knowledge of the mosquito life cycle, we summarise some of the more plausible impacts of microplastics including physiological, ecotoxicological and immunological responses. We conclude that although there remains little experimental evidence demonstrating any adverse effect on mosquito biology or pathogen transmission, significant knowledge gaps remain, and there is now a need to quantify the effects that microplastic pollution could have on such an important disease vector.

New records of pathogenic bacteria in different species of fleas collected from domestic and peridomestic animals in Spain. A potential zoonotic threat?

Climate change is causing many vectors of infectious diseases to expand their geographic distribution as well as the pathogens they transmit are also conditioned by temperature for their multiplication. Within this context, it is worth highlighting the significant role that fleas can play as vectors of important pathogenic bacteria. For this purpose, our efforts focused on detecting and identifying a total of 9 bacterial genera (Rickettsia sp.; Bartonella sp.; Yersinia sp.; Wolbachia sp., Mycobacterium sp., Leishmania sp., Borrelia sp., Francisella sp. and Coxiella sp.) within fleas isolated from domestic and peridomestic animals in the southwestern region of Spain (Andalusia). Over a 19-months period, we obtained flea samples from dogs, cats and hedgehogs. A total of 812 fleas was collected for this study. Five different species were morphologically identified, including C. felis, C. canis, S. cuniculi, P. irritans, and A. erinacei. Wolbachia sp. was detected in all five species identified in our study which a total prevalence of 86%. Within Rickettsia genus, two different species, R. felis and R. asembonensis were mainly identified in C. felis and A. erinacei, respectively. On the other hand, our results revealed a total of 131 fleas testing positive for the presence of Bartonella sp., representing a prevalence rate of 16% for this genus identifying two species B. henselae and B. clarridgeiae. Lastly, both Y. pestis and L. infantum were detected in DNA of P. irritans and C. felis, respectively isolated from dogs. With these data we update the list of bacterial zoonotic agents found in fleas in Spain, emphasizing the need to continue conducting future experimental studies to assess and confirm the potential vectorial role of certain synanthropic fleas.

Geographic expansion of the introduced Aedes albopictus and other native Aedes species in the Democratic Republic of the Congo

BackgroundAedes albopictus has been reported in several Central African countries, including the Democratic Republic of the Congo (DRC). The establishment of this mosquito species poses a serious threat as a vector of various infectious diseases. Although Ae. albopictus has been reported in the western region of the DRC, information about its distribution is still scarce in the country. The aim of this study was to investigate the current nationwide distribution of the invasive Ae. albopictus, as well as other native Aedes mosquitoes, in the DRC and to identify suitable areas for its future expansion.MethodsTwo entomological surveys were conducted in 2017–2019 and 2022. Based on the occurrence sites of Ae. albopictus, important environmental variables were identified. Then, geographical areas suitable for Ae. albopictus establishment were determined using the maximum entropy model. The distribution and abundance of Ae. albopictus were also compared with those of the major native Aedes species.ResultsAedes albopictus was found in the western, northern, central, and eastern regions of the DRC, but it was not found in the southeastern region. The maximum entropy model predicted that most parts of the DRC are suitable for the establishment of this mosquito. The unsuitable areas encompassed the eastern highlands, known for their low temperatures, and the southeastern highlands, which experience both low temperatures and a long dry season. The native Aedes species found were Aedes aegypti, Aedes simpsoni, Aedes africanus, and Aedes vittatus. Aedes albopictus dominated in the western and northern regions, while Ae. aegypti was more prevalent in other regions.ConclusionsAedes albopictus has been well established in the western and northern regions of the DRC. This mosquito is expanding its distribution while replacing the native Aedes species. Most of the country is suitable for the establishment of this mosquito species, except the highlands of the eastern and the southeastern regions.Graphical

Stability analysis of a SAIR epidemic model on scale-free community networks.

The presence of asymptomatic carriers, often unrecognized as infectious disease vectors, complicates epidemic management, particularly when inter-community migrations are involved. We introduced a SAIR (susceptible-asymptomatic-infected-recovered) infectious disease model within a network framework to explore the dynamics of disease transmission amid asymptomatic carriers. This model facilitated an in-depth analysis of outbreak control strategies in scenarios with active community migrations. Key contributions included determining the basic reproduction number, $ R_0 $, and analyzing two equilibrium states. Local asymptotic stability of the disease-free equilibrium is confirmed through characteristic equation analysis, while its global asymptotic stability is investigated using the decomposition theorem. Additionally, the global stability of the endemic equilibrium is established using the Lyapunov functional theory.

Phytochemical Screening and in-vitro Efficacy of Calpurnia aurea Against Two Transovarial Vectors: Amblyomma variegatum and Rhipicephalus microplus.

Ticks are the second most common vector of human infectious diseases after mosquitoes. Their transovarial transmission contributes to the maintenance of environmental diseases. This study evaluates the phytochemical screening and in vitro efficacy of Calpurnia aurea against the adult survival and egg hatchability of two transovarial transmission vectors: Amblyomma variegatum and Rhipicephalus microplus. Plant material was extracted using maceration techniques, and concentrated solutions of 12.5, 25, 50, 100, 200, and 400 ppm were prepared. Distilled water and diazinon were used as negative and positive controls, respectively. Ten adult ticks were exposed for 10 minutes, and dead ticks were counted after 24 hours of recovery. Twenty 15-day-old eggs were immersed for 10 minutes, and after 15 days of incubation, hatched and unhatched eggs were tallied. Preliminary phytochemical constituents were screened. A one-way analysis of variance and the probit regression model determined mean mortality and hatchability and estimated lethal and inhibitory concentrations, respectively. The ethanolic and aqueous leaf extracts caused 10±0.0% mortality in adult A. variegatum and R. microplus. The effective dose was LC50 of 27 and 29 ppm and LC50 of 37 and 41 ppm, respectively. At 400 ppm, the leaf ethanolic and aqueous extracts showed 18.7±0.9% and 18.3±1.7%; 18.3±1.2% and 19.7±0.3% egg hatching inhibition, respectively. The effective dose had an IC50 of 50 ppm and IC50s of 91 and 79 ppm, respectively. Flavonoids and saponins were found in both leaf and pod extracts. C. aurea extracts showed a more promising effect on tick survival and hatchability than synthetic diazinon. The susceptibility test indicated that the leaf extract could control vectors and contribute to environmental disease maintenance. Complex phytochemicals, especially phenolic compounds, are additional evidence of effectiveness in vector control. Further investigation of in vivo efficacy and advanced fractionation of phytochemicals is needed.

Diversity and seasonal dynamics analysis of the blood-sucking mosquitoes fauna (Diptera, Culicidae) of the Tavdinsky district of the Sverdlovsk region

This article provides data on the species diversity and seasonal dynamics of blood-sucking mosquitoes (Diptera, Culicidae), which are important vectors of various infectious and invasive diseases. As a result of the research conducted during several seasons from 2020 to 2022, it was revealed that 11 species of mosquitoes belonging to the genera Anopheles, Aedes and Culiseta live on the territory of the Tavdinsky district of the Sverdlovsk region. When comparing the number of culicids for all seasons, a correlation was revealed between hydrological, weather conditions and the intensity of insect summer. The optimal level of precipitation during the year provides enough breeding sites for mosquito larvae. The 2022 season was favorable for the development and summer of mosquitoes, in which heavy precipitation contributed to a vast area of reservoirs necessary for the development of insects. The smallest number was observed in 2021. As a result of low rainfall, severe frosts in winter, cold spring and arid, hot summer, there was a reduction in the number of mosquitoes. The results of the study allow a deeper understanding of the ecology of mosquitoes in this region, their activity in different seasons and their potential role in the transmission of infections. This work is important for the development of effective strategies for controlling mosquitoes and preventing diseases associated with their bites.

Fiebre y exantema tras picadura de garrapata

Hard ticks have become the main vectors of infectious diseases in the industrialized world, being able to transmit bacteria, viruses and protozoa through their bite, as well as causing allergic and toxic processes. Among the tick-borne disease the most frequent in our setting are boutonneuse fever, Lyme disease and Debonel/Tibola disease. Boutonneuse fever is the most common rickettsiosis in Europe. An increase in cases has been observed in recent years, probably related to the increase in global temperature.

Identification and Counting of Bacterial Colonies on Mobile Phones Before and After 70% Alcohol Disinfection

Cell phones have become a very important communication tool in everyday life. Considering that many people are in the habit of using their mobile phones while doing other activities, most people even have the habit of taking their phones to the toilet. Cell phones become inanimate objects that play an important role in the transmission of microorganisms. Therefore, we need to maintain hand hygiene by keeping our hands clean after handling the mobile phone before performing activities and disinfecting the mobile phone regularly, considering that this object cannot be washed while the mobile phone is a potential vector for infectious diseases. Mobile phones can effectively eliminate hand hygiene due to their compulsive use despite hand washing. The purpose of this study was to determine the role of 70% alcohol cotton on the surface of mobile phones to reduce the potential spread of bacteria. Based on the results of the research conducted, there is a difference in the number of bacterial colonies on mobile phones before and after disinfection with 70% alcohol cotton, as evidenced by the obtained p-value of 0.0001 (p &lt;0.05).

Molecular detection of virulence genes in Staphylococcus aureus isolated from wild pigeons (Columba domestica livia) in KwaZulu-Natal in South Africa

The current study aimed to determine virulence determinants among S. aureus isolated from wild pigeons and houseflies around hospital areas in the Greater Durban area, South Africa. Following enrichment and bacterial growth, DNA extraction using the boiling method was performed. Overall, 57 out of 252 samples (22.6%) were positive for S. aureus. Six known virulence genes were tested, where five known virulence determinants were positive and none of the S. aureus isolates were positive to coagulase (coa) gene. The highest prevalence rates were found in the genes encoding haemolysins, with the hla and hld genes having 8 (14%) and 9 (15.8%) positive isolates respectively. The sea, LukS/F-PV, and spa genes had 5 (8.8%), 4 (7%), and 2 (3.5%) positive isolates respectively. These results demonstrated the detection of pathogenic S. aureus from hospital environment in Durban, South Africa which may account for the emergence staphylococcal infections. The findings of the present study highlights the significant role of wild pigeons and houseflies as potenital infectious disease vectors in a One Health context.

Engineering a dual vaccine against COVID-19 and tuberculosis.

The COVID-19 pandemic, caused by SARS-CoV-2 virus, has been one of the top public health threats across the world over the past three years. Mycobacterium bovis BCG is currently the only licensed vaccine for tuberculosis, one of the deadliest infectious diseases in the world, that is caused by Mycobacterium tuberculosis. In the past decades, recombinant M.bovis BCG has been studied as a novel vaccine vector for other infectious diseases in humans besides tuberculosis, such as viral infections. In the current study, we generated a recombinant M. bovis BCG strain AspikeRBD that expresses a fusion protein consisting of M. tb Ag85A protein and the receptor-binding domain (RBD) of the SARS-CoV-2 spike protein using synthetic biology technique. Our results show that the recombinant M. bovis BCG strain successfully expressed this fusion protein. Interestingly, the recombinant M. bovis BCG strain AspikeRBD significantly induced SARS-CoV-2 spike-specific T cell activation and IgG production in mice when compared to the parental M.bovis BCG strain, and was more potent than the recombinant M.bovis BCG strain expressing SARS-CoV-2 spike RBD alone. As expected, the recombinant M. bovis BCG strain AspikeRBD activated an increased number of M. tb Ag85A-specific IFNγ-releasing T cells and enhanced IgG production in mice when compared to the parental M.bovis BCG strain or the BCG strain expressing SARS-CoV-2 spike RBD alone. Taken together, our results indicate a potential application of the recombinant M. bovis BCG strain AspikeRBD as a novel dual vaccine against SARS-CoV-2 and M. tb in humans.

Parasitism by Amblyomma ovale on domestic dog in the central region of the state of Rio Grande do Sul, Brazil

Ticks are obligate ectoparasite arthropods of the class Arachnida distributed worldwide and can parasitize many animals. They constitute one of the most important groups of vectors of infectious diseases, including zoonoses. The objective of this study was to report the parasitism by Amblyomma ovale Koch, 1844 in a domestic dog (Canis lupus familiaris Linnaeus, 1758) in Santa Maria, in the central region of the state of Rio Grande do Sul, Brazil. Two specimens of ectoparasites found on a domestic dog, living in a rural property, were sent to the Laboratory of Veterinary Parasitology at the Federal University of Santa Maria for taxonomic identification. The two specimens found were classified as adult male and female of A. ovale. Through this study, the parasitism of this species is reported for the first time in the central region of the state of Rio Grande do Sul, Brazil, in a domestic dog, allowing the infestation and transmission of diseases to humans.

Diet of the sylvatic triatomine Mepraia spinolai: Association with Trypanosoma cruzi infection near human settlements

The proximity between infectious disease vector populations and human settlements, and the infection prevalence of vector populations can determine the rate of encounters between vectors and humans and hence infection risk. The diet of sylvatic triatomine vectors (kissing bugs) provides evidence about the host species involved in the maintenance of the protozoan Trypanosoma cruzi, the etiological agent of Chagas disease. Here, we characterized the diet of the Chilean endemic triatomine Mepraia spinolai using Next Generation Sequencing (NGS), and evaluated the relation between T. cruzi infection status and proximity to human settlements, with the proportion of human and human-associated (domestic and synanthropic) vertebrates in the diet. We sampled 28 M. spinolai populations, covering a latitudinal range of ∼800 km in Chile. For each population, genomic DNA was obtained from M. spinolai intestinal content. We assessed T. cruzi infection individually, and sequenced vertebrate cytochrome b to characterize the diet from infected and uninfected pooled samples. Human and human-associated animals were present in the diet of both T. cruzi-infected (13.50 %) and uninfected (10.43 %) kissing bugs. The proportion of human and human-associated vertebrates in the diet of infected M. spinolai was negatively associated with the distance from surrounding human settlements, but no relationship was detected for uninfected kissing bugs. This pattern could be related to alterations of kissing bug feeding behavior when infected by the protozoan. Our results highlight the relevance of developing a deeper knowledge of the wild transmission cycle of T. cruzi, thus advancing in the surveillance of vectors present in the natural environment near human settlements.

Ticks are unlikely to play a role in leprosy transmission in the Comoros (East Africa) as they do not harbour M. leprae DNA.

Leprosy, one of the oldest known human diseases, continues to pose a global challenge for disease control due to an incomplete understanding of its transmission pathways. Ticks have been proposed as a potential contributor in leprosy transmission due to their importance as vectors for other infectious diseases. In 2010, a sampling of ticks residing on cattle was conducted on the islands Grande Comore, Anjouan, and Mohéli which constitute the Union of the Comoros where leprosy remains endemic. To investigate the potential role of ticks as a vector in transmission of leprosy disease, molecular analyses were conducted. Out of the 526 ticks analysed, none were found to harbour Mycobacterium leprae DNA, as determined by a quantitative polymerase chain reaction (qPCR) assay targeting a family of dispersed repeats (RLEP) specific to M. leprae. Therefore, our results suggest that in the Union of the Comoros, ticks are an unlikely vector for M. leprae.